Various article sortation systems have been employed in the merchandising and processing of articles and parcels. Such systems require rapid and reliable transportation of the articles from a loading station to one of any number of unloading stations or destinations. These systems are commonly used in airport terminals to sort baggage, in post offices to sort mail, and in warehouses to sort delivered articles to selected storage areas in the warehouses. Article sortation systems must be capable of handling a wide variety of articles which are placed on trays for conveying and sorting. Present day article sortation systems operate at speeds which enable them to transport articles adequately. As the speeds of the carrying trays increase to allow for the sorting of greater quantities of articles, difficulties have surfaced in discharging the articles from the carrying trays at the article destination points or sortation lanes. Some of these difficulties involve the articles being thrown or tumbled from the trays during discharging, which can cause damage to the article. Another difficulty involves the accuracy of article discharge which results in articles being improperly sorted and the like.
The prior art has made many attempts to solve these difficulties by providing conveyor systems which unload carried articles by some type of tray tilting operation. For example, U.S. Pat. No. 4,461,378 to Roth discloses a power driven conveyer assembly which has a supporting framework that defines a conveyor pathway. A conveyor belt follows the pathway and has a top surface which is adapted for carrying articles. The belt is then tilted to one side of the pathway to discharge the carried articles. Another example can be seen in U.S. Pat. No. 3,360,106 to Harrison et al. which discloses a continuous conveyor system having a carriage mechanism with individual trays mounted thereon. Each tray is supported on the carriage by a linkage assembly that can tilt the tray in either direction. Many other article sortation systems employing article discharge by tray tilting are described in the prior art.
A major disadvantage of these prior art article sortation systems lies in their mechanical complexity which results in high capital costs and high maintenance costs. Further, the mechanical complexity of prior art sortation systems may result in less than desirable reliability. Moreover, the gentleness and accuracy with which articles are discharged in some prior art sortation systems leaves much to be desired.
Therefore, a need exists for a simpler and less expensive article sortation system which is capable of sorting a wide variety of articles in an accurate and gentle manner.